The breakdown:
Having just completed a 2200 mile trip to Indianapolis, IN and back, my 100 was running great, until the next day. On that day, I drove north of town (in a blizzard and salt/slop storm) and I heard a faint 'click' while driving and the engine died at 55 mph. I peeled over to the right shoulder and waited 3 hours for AAA to show up, while plow trucks and nutty drivers tried to hit me. I called a buddy to give my patient wife a ride home.
At the road side, I pulled the fuel filter outlet line, and the fuel pump was emitting no fuel at the filter, which was my quick road-side diagnostic. All fuses seemed good, and I replaced the pump and filter last August with Aisin/OEM ($300). See the 'photo of shame' getting loaded on the tow truck. So, I had no fuel, but no idea why! No easy roadside fix and no MIL codes or check-engine light.
Initial diagnostics:
The tow truck driver offloaded the ice-crusted truck directly into my garage (very stylish!) and the next day, I began the long road of following the FSM and debugging. What was really odd is that after hot wiring the fuel pump relay (per medtro's post), it would occasionally start and run, but a subsequent restart would fail. The fuel pump had a mind of its own. No MIL codes, by the way, at any point.
Testing per FSM:
I tested the fuel pump according to the FSM, and it hummed, but produced no fuel. I pulled my new pump assembly, stuck it into a 2 lb. coffee can full of gas (remember those?) and it blew bubbles, instead of pumping fuel. The @#$#%^ Toyota FSM had the polarity backward in their step! I kid you not. Swapping the wire resulted in a geyser of fuel, so my pump was fine, so I reinstalled it.
I bought a fuel pump ECU and relay at a junkyard ($50/both) because I was getting odd readings at the fuel pump ECU and odd voltages at the pump. The pump showed .25v (at the pump) with the engine off! And ~10v during cranking (not within spec).
The breakthrough:
I invited over a co-worker of mine, who is a former Toyota tech and owns a laptop with Techstream. We connected it and commanded the fuel pump to run, and it didn't. He and I then got a quality VOM and started tracing each wire from the fuel pump ECU to the pump itself. The fat black wire showed 9.8 megaohms (!) between the ECU and pump. Err - should be 0 ohms. At that point, we had to quit our work.
The repair:
So today, I flexed the harness below the driver's rear door, which feeds the pump. The bright-green verdigris peeking out was the telltale smoking gun. Only this fat black ground wire was heavily corroded and broke upon disassembly (all other wires were fine). Fortunately, you can pull this harness section up through the floor and fix it easily and then pass it back through the floor. I cut the wire back until I found sound (non-corroded) wire, soldered on quality wire, greased it all with silicone grease, and covered it with heat-shrink tubing. I realize there are more elegant fixes, but I think mine is sound and stout.
Upon reassembly of the harness, all was well and the fuel pump shot fuel out of the filter, and when reconnected, the engine fired up as it should. I did some high RPM runs, and all seems well.
Learnings:
The takeaway? Not all 100 series fuel pump problems are with the pump itself or the control system (fuse and relay). I likely have 20 hours into this repair, and fortunately could drive my FJ62 all week (never a bad thing). I can't imagine what a dealer would have done with this, besides evacuate my wallet.
Part of the time I spent/wasted was in learning how the the control system for the pump works, and only after that, can you better understand where to begin troubleshooting. I can't say I have ever had a wire failure like this on any of the dozens of old Toyota I have owned, including older FJ40s, 55s, 60s, etc. Live and learn. Hat tip to all the Mud posters who have shared their stories to give me background info.
Steve
Having just completed a 2200 mile trip to Indianapolis, IN and back, my 100 was running great, until the next day. On that day, I drove north of town (in a blizzard and salt/slop storm) and I heard a faint 'click' while driving and the engine died at 55 mph. I peeled over to the right shoulder and waited 3 hours for AAA to show up, while plow trucks and nutty drivers tried to hit me. I called a buddy to give my patient wife a ride home.
At the road side, I pulled the fuel filter outlet line, and the fuel pump was emitting no fuel at the filter, which was my quick road-side diagnostic. All fuses seemed good, and I replaced the pump and filter last August with Aisin/OEM ($300). See the 'photo of shame' getting loaded on the tow truck. So, I had no fuel, but no idea why! No easy roadside fix and no MIL codes or check-engine light.
Initial diagnostics:
The tow truck driver offloaded the ice-crusted truck directly into my garage (very stylish!) and the next day, I began the long road of following the FSM and debugging. What was really odd is that after hot wiring the fuel pump relay (per medtro's post), it would occasionally start and run, but a subsequent restart would fail. The fuel pump had a mind of its own. No MIL codes, by the way, at any point.
Testing per FSM:
I tested the fuel pump according to the FSM, and it hummed, but produced no fuel. I pulled my new pump assembly, stuck it into a 2 lb. coffee can full of gas (remember those?) and it blew bubbles, instead of pumping fuel. The @#$#%^ Toyota FSM had the polarity backward in their step! I kid you not. Swapping the wire resulted in a geyser of fuel, so my pump was fine, so I reinstalled it.
I bought a fuel pump ECU and relay at a junkyard ($50/both) because I was getting odd readings at the fuel pump ECU and odd voltages at the pump. The pump showed .25v (at the pump) with the engine off! And ~10v during cranking (not within spec).
The breakthrough:
I invited over a co-worker of mine, who is a former Toyota tech and owns a laptop with Techstream. We connected it and commanded the fuel pump to run, and it didn't. He and I then got a quality VOM and started tracing each wire from the fuel pump ECU to the pump itself. The fat black wire showed 9.8 megaohms (!) between the ECU and pump. Err - should be 0 ohms. At that point, we had to quit our work.
The repair:
So today, I flexed the harness below the driver's rear door, which feeds the pump. The bright-green verdigris peeking out was the telltale smoking gun. Only this fat black ground wire was heavily corroded and broke upon disassembly (all other wires were fine). Fortunately, you can pull this harness section up through the floor and fix it easily and then pass it back through the floor. I cut the wire back until I found sound (non-corroded) wire, soldered on quality wire, greased it all with silicone grease, and covered it with heat-shrink tubing. I realize there are more elegant fixes, but I think mine is sound and stout.
Upon reassembly of the harness, all was well and the fuel pump shot fuel out of the filter, and when reconnected, the engine fired up as it should. I did some high RPM runs, and all seems well.
Learnings:
The takeaway? Not all 100 series fuel pump problems are with the pump itself or the control system (fuse and relay). I likely have 20 hours into this repair, and fortunately could drive my FJ62 all week (never a bad thing). I can't imagine what a dealer would have done with this, besides evacuate my wallet.
Part of the time I spent/wasted was in learning how the the control system for the pump works, and only after that, can you better understand where to begin troubleshooting. I can't say I have ever had a wire failure like this on any of the dozens of old Toyota I have owned, including older FJ40s, 55s, 60s, etc. Live and learn. Hat tip to all the Mud posters who have shared their stories to give me background info.
Steve
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